The goal of this project is to develop a Haemophilus influenzae b vaccine that does not involve randomness of derivatization and conjugate reactions, as occurs in current vaccines. The approach to this problem is based on the similarities between DNA and polyribosylribitolphosphate (PRP), each of which consists of a chain of saccharide units linked together with phosphodiester bonds. It has been reported that by treatment with 1-(3-dimethylaminopropyl)-3-ethylcarboniimide (EDAC) it is possible to derivatize exclusively a terminal phosphate group of DNA at the 5~ end with diamine derivative. The same approach was applied to modify the PRP. In total, 12 amine PRP derivatives were prepared. They differ by lengths of alkyl chains. The diamines with different lengths were chosen in order to examine whether the length of linker has an effect on the immunogenicity of glycoconjugates. The second kind of linker, hydrazide derivative of biotin with different lengths of hydrazide molecules, was used to prepare six derivatives. The biotin modified PRP derivatives will be used for making complexes with avidin, streptavidin, or neutravidin. Following purification, the presence of PRP in collected fractions was monitored by HPLC, and corresponding fractions were assayed for sugar content by orcinol assay. The amount of Hib in 18 derivatives ranged from 1400 to 2600 ug/mL. The concentration of amine in 12 derivatives was assayed by TNBS, and varied from 5 to 75 ug/mL proportionally with the concentration of the activator (EDAC). The amount of biotin measured with HABA reagent ranged from 6 to 7 ug/mL. Accordingly, the degree of derivatization of PRP, i.e., the w/w ratio of amine or biotin per PRP, varied from 0.002 to 0.03.